posts-go/docs/2022-10-26-reload-config.html

<!doctype html><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><link rel=preconnect href=https://fonts.googleapis.com><link rel=preconnect href=https://fonts.gstatic.com crossorigin><link href="https://fonts.googleapis.com/css2?family=Recursive:wght,CASL,MONO@300..800,0..1,0..1&display=swap" rel=stylesheet><link href=https://haunt98.github.io/iosevka_webfont/iosevka-term-ss08/iosevka-term-ss08.css rel=stylesheet><link rel=stylesheet href=styles.css><a href=index>Index</a><h1>Reload config</h1><p>This serves as design draft of reload config system<pre><code class=language-plantuml>@startuml Reload config

skinparam defaultFontName Iosevka Term SS08

participant admin
participant other_service
participant config_service
participant storage

== Admin handle ==

admin -&gt; config_service: set/update/delete config

config_service -&gt; storage: set/update/delete config

== Other service handle ==

other_service -&gt; other_service: init service

activate other_service

other_service -&gt; storage: make connection

loop

    other_service -&gt; storage: listen on config change

    other_service -&gt; other_service: save config to memory

end

deactivate other_service

other_service -&gt; other_service: do business

activate other_service

other_service -&gt; other_service: get config

other_service -&gt; other_service: do other business

deactivate other_service

@enduml
</code></pre><p>Config storage can be any key value storage or database like etcd, Consul, mySQL, ...<p>If storage is key value storage, maybe there is API to listen on config change.<br>Otherwise we should create a loop to get all config from storage for some interval, for example each 5 minute.<p>Each <code>other_service</code> need to get config from its memory, not hit <code>storage</code>.<br>So there is some delay between upstream config (config in <code>storage</code>) and downstream config (config in <code>other_service</code>), but maybe we can forgive that delay (???).<p>Pros:<ul><li><p>Config can be dynamic, service does not need to restart to apply new config.<li><p>Each service only keep 1 connection to <code>storage</code> to listen to config change, not hit <code>storage</code> for each request.</ul><p>Cons:<ul><li>Each service has 1 more dependency, aka <code>storage</code>.<li>Need to handle fallback config, incase <code>storage</code> failure.<li>Delay between upstream/downstream config</ul><a href=mailto:hauvipapro+posts@gmail.com>Feel free to ask me via email</a>
<a rel=me href=https://hachyderm.io/@haunguyen>Mastodon</a>
chore: gen html 2022-10-26 15:08:03 +00:00			<!doctype html><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><link rel=preconnect href=https://fonts.googleapis.com><link rel=preconnect href=https://fonts.gstatic.com crossorigin><link href="https://fonts.googleapis.com/css2?family=Recursive:wght,CASL,MONO@300..800,0..1,0..1&display=swap" rel=stylesheet><link href=https://haunt98.github.io/iosevka_webfont/iosevka-term-ss08/iosevka-term-ss08.css rel=stylesheet><link rel=stylesheet href=styles.css><a href=index>Index</a><h1>Reload config</h1><p>This serves as design draft of reload config system<pre><code class=language-plantuml>@startuml Reload config

			`skinparam defaultFontName Iosevka Term SS08`

			`participant admin`
			`participant other_service`
			`participant config_service`
			`participant storage`

			`== Admin handle ==`

			`admin -> config_service: set/update/delete config`

			`config_service -> storage: set/update/delete config`

			`== Other service handle ==`

			`other_service -> other_service: init service`

			`activate other_service`

			`other_service -> storage: make connection`

			`loop`

			`other_service -> storage: listen on config change`

			`other_service -> other_service: save config to memory`

			`end`

			`deactivate other_service`

			`other_service -> other_service: do business`

			`activate other_service`

			`other_service -> other_service: get config`

			`other_service -> other_service: do other business`

			`deactivate other_service`

			`@enduml`
chore: add rel=me to mastodon 2022-11-26 05:03:16 +00:00			</code></pre><p>Config storage can be any key value storage or database like etcd, Consul, mySQL, ...<p>If storage is key value storage, maybe there is API to listen on config change.<br>Otherwise we should create a loop to get all config from storage for some interval, for example each 5 minute.<p>Each <code>other_service</code> need to get config from its memory, not hit <code>storage</code>.<br>So there is some delay between upstream config (config in <code>storage</code>) and downstream config (config in <code>other_service</code>), but maybe we can forgive that delay (???).<p>Pros:<ul><li><p>Config can be dynamic, service does not need to restart to apply new config.<li><p>Each service only keep 1 connection to <code>storage</code> to listen to config change, not hit <code>storage</code> for each request.</ul><p>Cons:<ul><li>Each service has 1 more dependency, aka <code>storage</code>.<li>Need to handle fallback config, incase <code>storage</code> failure.<li>Delay between upstream/downstream config</ul><a href=mailto:hauvipapro+posts@gmail.com>Feel free to ask me via email</a>
			`<a rel=me href=https://hachyderm.io/@haunguyen>Mastodon</a>`